It is known in the prior art to provide speed command information for controlling a transit vehicle by multiplex coding as described in an article entitled "The BARTD Train Control System" that was published in Railway Signaling & Communications for December 1967 at pages 18 to 23. The extraction of this coded speed command information is by a well-known timing track signal including a word pulse followed by a plurality of time slot pulses, with the word pulse comprising a space used for synchronization purposes so the proper time slot and corresponding track circuit can be selected for the respective information bits of the speed command data. The data down information including the multiplex speed code is provided to all the transmitter receivers operative with the transit vehicle. Each transmitter and receiver is assigned a particular track circuit and a specified time slot. The time slot scanner is provided to pick up data for a particular time slot and enable the corresponding transmitter to be operative with that assigned time slot data. The word pulses synchronize the operation such that the desired data for a given time slot is picked up from the data down information. A six-bit speed code is transmitted in six successive sequences of this word pulse with each word pulse being the beginning of a new sequence such that it would take six word pulse sequences to reconstruct the complete six-bit speed code. The receiver for each track circuit is operative such that the signal coming from the track circuit will be decoded as a six-bit code and the time slot will take off that data one bit at a time and put it on the multiplex data line going back to the station multiplex cabinet as data back. In the station multiplex cabinet, there is a bit-by-bit comparator which compares in a fail-safe manner the data sent to the track circuit with the data coming back from the track circuit to determine if the particular track circuit is occupied or not. In the prior art, each track circuit had its associated wayside time slot scanner for a particular time slot assigned to that track circuit, and in this manner picked off the data from the multiplex line, which data was desired for that particular track circuit, such that it would pick off the speed command information one bit at a time as it appeared on the same time slot in each sequential operation determined by the word pulse associated with the speed code pulses.